Filtration media have been used for the filtration of fine particles from fluids, particularly liquids, for many years. Such filtration media are available in a variety of materials to meet particular filtration requirements. Fibrous webs, such as those described in U.S. Pat. No. 4,021,281, are particularly well-suited to the filtration of certain particulate matters from fluids.
Fibrous webs possess the ability to remove certain particles from fluids but unfortunately suffer from a lack of mechanical strength, e.g., they are readily deformed. As a result, a support material is often mated with such a fibrous web in order to provide a filtration medium with satisfactory mechanical characteristics. This is particularly the case when the filtration medium is used in high shear or pulsed flow environments or is subjected to high backflow pressures.
There have been many attempts at mating fibrous webs to suitable support materials. These attempts have included melt-blowing a fibrous web directly onto a support material, thermally laminating a fibrous web directly onto a support material, and utilizing an adhesive to secure a fibrous web to a support material. Each of these techniques is not without problems, such as weak fibrous web-support adherence, significant blockage of the pores of the fibrous web and/or support material, alteration of the physical characteristics of the fibrous web, and the introduction of possible contamination sources.
Thus, there remains a need for a method for adhering a fibrous web to the surface of a support material, particularly a rigid support material, which method provides secure adherence of the fibrous web to the support material without substantially adversely affecting either the fibrous web or the support material. The present invention seeks to provide such a method and the resulting supported fibrous web assembly. These and other objects and advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention set forth herein.